Non-propulsive utility power (npup) generation system for providing secondary power in an aircraft

ABSTRACT

An aircraft may include at least one secondary power system requiring secondary power, at least two main engines, and at least three non-propulsive utility power (NPUP) generation systems. The NPUP generation systems may each be configured to provide full-time secondary power during operation of the aircraft. The NPUP generation systems may be configured to provide at least a portion of the secondary power required by the secondary power system.

FIELD

The disclosed system and method relate to an aircraft and, more particularly, to an aircraft having multiple non-propulsive utility power (NPUP) generation systems each configured to provide full-time secondary power during operation of the aircraft.

BACKGROUND

Non-propulsive aircraft systems are typically driven by a combination of different secondary power types such as hydraulic, pneumatic, electrical and mechanical power, which may all be extracted from an aircraft's main engines using various approaches. For example, pneumatic power may be provided by extracting bleed air from various compressor stages of the main engine, and mechanical power may be extracted from a gearbox driven by the output shaft of the main engine. However, extracting energy reduces the engine total efficiency and thereby increases the specific fuel consumption of the main engine. Moreover, the machinery used to extract energy from the main engine may need to be placed within very confined areas of the aircraft, where packaging space is limited. Specifically, the machinery may be placed within the main engine and an associated nacelle that surrounds the main engine. In addition, the machinery may also result in an increased inner to outer wall thickness of the nacelle. Increasing the inner to outer wall thickness will in turn increase the weight and drag associated with the nacelle. The machinery also adds cost and weight to the aircraft as well.

One or more auxiliary power units (APUs) may be included in the aircraft to provide non-propulsive power. However, the APUs are typically treated as a back-up power source, and are infrequently used while the aircraft is in flight. For example, in one approach the APU may serve as an on-line emergency electrical power source in the event a main engine generator or one of the main engines become inoperative.

SUMMARY

In one embodiment, an aircraft may include at least one secondary power system requiring secondary power, at least two main engines, and at least three non-propulsive utility power (NPUP) generation systems. The NPUP generation systems may each be configured to provide full-time secondary power during operation of the aircraft. The NPUP generation systems may be configured to provide at least a portion of the secondary power required by the secondary power system.

In another embodiment, a method of providing secondary power in an aircraft may be disclosed, where the aircraft may include at least one secondary power system and at least two main engines. The secondary power system may require the secondary power. The method may include generating at least a portion of the secondary power required by the secondary power system by at least three non-propulsive utility power (NPUP) generation systems. Each NPUP generation system may be configured to provide full-time secondary power during operation of the aircraft.

In yet another embodiment, an aircraft may include a plurality of electrical power systems requiring electrical power, at least one hydraulic power system requiring hydraulic power, at least two main engines, and at least two non-propulsive utility power (NPUP) generation systems. The NPUP generation systems may each be configured to provide full-time secondary power during operation of the aircraft. The NPUP generation systems may be configured to provide at least a portion of the electrical power required by the electrical systems.

Other objects and advantages of the disclosed method and system will be apparent from the following description, the accompanying drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an embodiment of the disclosed aircraft including a propulsive power system and a secondary power system;

FIG. 2 is a block diagram of the propulsive power system and the secondary power system shown in FIG. 1, where the secondary power system may include a pneumatic power system, an electrical power system, and a hydraulic power system;

FIG. 3 is a schematic view an embodiment of the disclosed secondary power system in the aircraft, where the secondary power system may include two non-propulsive utility power (NPUP) generation sources, a pneumatic system, an electrical system, and a hydraulic system;

FIG. 4 is a schematic view of another embodiment of the secondary power system shown in FIG. 3;

FIG. 5 is a schematic view of yet another embodiment of the secondary power system shown in FIG. 3, where the secondary power system includes three NPUP generation sources;

FIG. 6 is a schematic view of another embodiment of the secondary power system shown in FIG. 3, where the secondary power system includes three NPUP generation sources;

FIG. 7 is a schematic view of yet another embodiment of the secondary power system shown in FIG. 3, where the secondary power system includes three NPUP generation sources;

FIG. 8 is a schematic view of another embodiment of the secondary power system shown in FIG. 3, where the secondary power system includes four NPUP generation sources;

FIG. 9 is a schematic view of yet another embodiment of the secondary power system shown in FIG. 3, where the secondary power system includes four NPUP generation sources;

FIG. 10 is a schematic view of another embodiment of the secondary power system shown in FIG. 3, which may include two NPUP generation sources, an electrical system, and a hydraulic system;

FIG. 11 is a schematic view of yet another embodiment of the secondary power system shown in FIG. 3, which may include two NPUP generation sources, an electrical system, and a hydraulic system;

FIG. 12 is a schematic view of another embodiment of the secondary power system shown in FIG. 3, which may include two NPUP generation sources, an electrical system, and a hydraulic system;

FIG. 13 is a schematic view of yet another embodiment of the secondary power system shown in FIG. 3, which may include three NPUP generation sources, an electrical system, and a hydraulic system;

FIG. 14 is a schematic view of another embodiment of the secondary power system shown in FIG. 3, which may include three NPUP generation sources, an electrical system, and a hydraulic system;

FIG. 15 is a schematic view of yet another embodiment of the secondary power system shown in FIG. 3, which may include three NPUP generation sources, an electrical system, and a hydraulic system; and

FIG. 16 is a schematic view of another embodiment of the secondary power system shown in FIG. 3, which may include four NPUP generation sources, an electrical system, and a hydraulic system.

DETAILED DESCRIPTION

As shown in FIG. 1, the disclosed aircraft, generally designated 2, may include a propulsive power system 4 and a secondary power system 6. The propulsive power system 4 may be used to provide propulsive thrust to the aircraft 2, and the secondary power system 6 may be used to provide secondary power to the aircraft 2. Secondary power may also be referred to as non-propulsive power or utility power. The propulsive power system 4 may include two main engines, which are illustrated in FIG. 1 as a left main engine 20 a and a right main engine 20 b. It should be noted that while two main engines are illustrated, it is to be understood that in another embodiment, the aircraft 2 may include more than two main engines as well. The secondary power system 6 may include at least one secondary power generation system 10, at least one secondary distribution system 11, and at least one utility or consumption system 12.

The secondary power generation system 10 may include a non-propulsive utility power (NPUP) system 13 and a main engine extraction system 14. The main engine extraction system 14 may be used to extract power from the main engines 20 a, 20 b. The NPUP system 13 may include a power generation system 15, a power conversion system 16, and a power control system 17. In one embodiment, the power generation system 15 may include at least two NPUP generation sources, which are illustrated as NPUP generation source 22 a and NPUP generation source 22 b. Although FIG. 1 illustrates two NPUP generation sources 22 a, 22 b, it is to be understood that the power generation system 15 may also include three NPUP generation sources (illustrated in FIGS. 5-7 and 12-15) or four NPUP generation sources (illustrated in FIGS. 8-9 and 16) as well. The NPUP generation sources 22 a, 22 b may be any device capable of providing non-propulsive or secondary energy to the aircraft 2 such as, for example, a gas turbine engine, an internal combustion engine, or a fuel cell. In one non-limiting embodiment, the NPUP generation sources 22 a, 22 b may each be coupled to an energy storage system (not illustrated). The energy storage system may include any type of device capable of storing energy such as, for example, a flywheel, a capacitor, a hydraulic accumulator, a pneumatic accumulator, or a battery, and may be used during load peaking of the aircraft 2.

Referring to FIG. 2, in one embodiment the secondary power system 6 may include a pneumatic power system 6 a, an electrical power system 6 b, and a hydraulic power system 6 c. It should be noted that the illustration of FIG. 2 is exemplary in nature, and the secondary power system 6 may include other types of power systems as well. For example, in one embodiment the secondary power system 6 may also include a mechanical power system (not shown) for providing mechanical shaft power. The NPUP generation sources 22 a, 22 b may be used to provide power to the pneumatic power system 6 a, the electrical power system 6 b, and the hydraulic power system 6 c. In other words, the power generation system 15 may be shared among the various secondary power systems. However, the pneumatic power system 6 a, the electrical power system 6 b, and the hydraulic power system 6 c may each include a unique power conversion system, power control system and main engine extraction system.

In one embodiment, the pneumatic power system 6 a may include a pneumatic power conversion system 16 a and a pneumatic power control system 17 a. The pneumatic power conversion system 16 a may include at least two pneumatic compressors, which are illustrated in FIG. 3 as pneumatic compressors 44 a, 44 b. The pneumatic control system 17 a may include various controller devices (not shown) such as, for example, electronic circuitry and microprocessors that may be used to control the amount of pneumatic power extracted from the NPUP generation sources 22 a, 22 b. For example, the pneumatic control system 17 a may control the position of one or more of pneumatic valves 42 a, 42 b, 43 c (shown in FIG. 3). A pneumatic main engine extraction system 14 a may include componentry (not shown) for extracting bleed air from various compressor stages (not shown) of the main engines 20 a, 20 b.

The electrical power system 6 b may include an electrical power conversion system 16 b and an electrical power control system 17 b. The electrical power conversion system 16 b may include at least two electrical generators each coupled to one of the NPUP generation sources 22 a, 22 b, which are illustrated in FIG. 3 as a left NPUP generator 72 a and a right NPUP generator 72 b. The electrical control system 17 b may also include various controller devices (not shown) for controlling the amount of electrical power extracted from the NPUP generation sources 22 a, 22 b. For example, the electrical control system 17 b may be used to engage the NPUP generators 72 a, 72 b (shown in FIG. 3). The electrical main engine extraction system 14 b may include a left propulsive engine generator 70 a and a right propulsive engine generator 70 b, which are also shown in FIG. 3.

The hydraulic power system 6 c may include a hydraulic power conversion system 16 c and a hydraulic power conversion system 17 c. The hydraulic power conversion system 16 c may include at least two NPUP hydraulic pumps, which are illustrated in FIG. 7 as left NPUP hydraulic pump 484 a and right NPUP hydraulic pump 484 b. The hydraulic control system 17 b may also include various controller devices (not shown) for controlling the amount of hydraulic power extracted from the NPUP generation sources 22 a, 22 b. For example, the hydraulic control system 17 c may be used to activate the NPUP hydraulic pumps 484 a, 484 b (shown in FIG. 7). A hydraulic main engine extraction system 14 c may include a left propulsive engine hydraulic pump 84 a and a right propulsive engine hydraulic pump 84 b (shown in FIG. 3).

Referring to FIG. 2, the pneumatic power system 6 a, the electrical power system 6 b, and the hydraulic power system 6 c may also each include a unique secondary distribution system and a unique consumption system as well. For example, the pneumatic power system 6 a may include a pneumatic distribution system 11 a. The pneumatic distribution system 11 a may include at least two pneumatic distribution channels, which are illustrated in FIG. 3 as a left pneumatic distribution channel 36 a, and a right pneumatic distribution channel 36 b. The pneumatic power system 6 a may also include a consumption system 12 a such as, for example, an environmental control system (ECS), which is illustrated in FIG. 3 as ECSs 50 a, 50 b. The electrical power system 6 b may include an electrical distribution system 11 b. The electrical distribution system 11 b may include a plurality of electrical busses, which are illustrated in FIG. 3 as electrical busses 76 a-76 d. The electrical power system 6 b may also include an electrical consumption system 12 b which may consume electrical power. Some examples of the electrical consumption system 12 b include, but are not limited to, cabin systems, galley systems, and flight deck avionics systems. The hydraulic power system 6 c may include a hydraulic distribution system 11 c, which is illustrated in FIG. 3 as left hydraulic distribution channel 82 a and right hydraulic distribution channel 82 b. The hydraulic power system 6 c may also include a hydraulic consumption system 12 c such as, for example, actuators for flight controls and landing gear. The hydraulic power system 6 c consumes hydraulic power, and is illustrated in FIG. 3 as a left hydraulic system 78 a and a right hydraulic system 78 b.

Referring to FIG. 3, a schematic illustration of the aircraft 2 is shown. The aircraft 2 may include a left NPUP generation system 24 a, a right NPUP generation system 24 b, a left main engine extraction system 26 a, and a right main engine extraction system 26 b. The left NPUP generation system 24 a may include the left NPUP generation source 22 a. Similarly, the right NPUP generation system 24 b may include the right NPUP generation source 22 a. Each of the NPUP generation systems 24 a, 24 b may operate independently with respect to each another. That is, each of the NPUP generation systems 24 a, 24 b may be installed on the aircraft 2 as an independent system, where the left NPUP generation system 24 a may be functionally and physically isolated from the right NPUP generation system 24 b. The NPUP generation systems 24 a, 24 b may each be utilized as full-time secondary power generation systems during operation of the aircraft 2. This means that the NPUP generation systems 24 a, 24 b provide secondary power when the aircraft 2 is on the ground as well as during all phases of flight. Thus, the main engines 20 a, 20 b may not typically be used as the primary source of secondary power.

The aircraft 2 may include at least two NPUP generation systems 24 a, 24 b in order to provide redundancy, which may be required for certification purposes. For example, one or both of the NPUP generation systems may be operated substantially under capacity during normal operation of the aircraft 2. Thus, if a transient condition occurs that affects operation of the right NPUP generation system 24 b, then the left NPUP generation system 24 a or the main engines 20 a, 20 b may be used as an alternate, independent source of power capable of maintaining aircraft essential loads. An aircraft essential load may be defined as a load required for certification of the aircraft 2. Likewise, a non-essential load may be defined as a load that is not required for certification of the aircraft 2.

The NPUP generation systems 24 a, 24 b may generate at least a portion of the secondary power required by the consumption systems 12 (shown in FIGS. 1-2) located within the aircraft 2. As described above, the consumption systems 12 may include, but are not limited to, hydraulic systems, flight control systems, fuel systems, landing gear systems, the ECSs 50 a and 50 b, flight deck avionics systems, cabin systems, galley systems, and lavatory systems. The NPUP generation systems 24 a, 24 b may also be used to drive aircraft wheels (not shown) when the aircraft 2 is taxiing. In the exemplary embodiment as shown in FIG. 3, the aircraft 2 includes a pneumatic system 30, an electrical system 32, and two hydraulic systems 34 a, 34 b. The pneumatic system 30 may be used to provide pneumatic power to the ECSs 50 a, 50 b. The electrical system 32 may be used to provide electrical power to various electrical consumption systems (not illustrated in FIG. 3) such as, for example, flight control systems and flight deck avionics systems that may be coupled to independent electrical busses 88 a-88 d. Similarly, the hydraulic systems 34 a, 34 b may each be used to provide hydraulic power to the corresponding left and right hydraulic systems 78 a, 78 b.

Although FIG. 3 illustrates the aircraft 2 including the pneumatic system 30, the electrical system 32, and two hydraulic systems 34 a, 34 b, it is to be understood that the aircraft 2 may include other system configurations as well. For example, in the embodiments as shown in FIGS. 10-16, the aircraft only includes an electrical system and a hydraulic system, and are described in greater detail below. It should also be noted that while two hydraulic systems 34 a, 34 b are illustrated in FIG. 3, the aircraft 2 may only include one hydraulic system as well. Moreover, in another embodiment the aircraft 2 may include a third hydraulic system (not shown) as well, which may be powered by an electric, mechanical shaft or pneumatic air source.

The NPUP generation systems 24 a, 24 b may be used to generate at least a portion of the secondary or non-propulsive power required by the aircraft 2. Specifically, depending on the specific architecture of the secondary power system 10, the NPUP generation systems 24 a, 24 b may generate anywhere from about fifty percent to about one hundred percent of the secondary power required by the consumption systems 12 (shown in FIGS. 1-2) located within the aircraft 2. The remaining secondary power not provided by the NPUP generation systems 24 a, 24 b may be extracted from the main engines 20 a, 20 b by the main engine extraction systems 26 a, 26 b. However, in some embodiments the NPUP generation systems may be used to provide substantially all of the secondary power required by the consumption systems 12 (shown in FIGS. 1-2) located within the aircraft 2, thus generally eliminating the need to extract energy from the main engines 20 a, 20 b. Specifically, in the embodiments as shown in FIGS. 8, 13, and 15-16, the NPUP generation systems provide substantially all of the secondary or non-propulsive power required by the aircraft.

In the embodiment as shown in FIG. 3, the NPUP generation systems 24 a, 24 b may provide between about fifty percent to about ninety percent of the secondary power required by the consumption systems 12 (shown in FIGS. 1-2) located within the aircraft 2 during normal operation. The specific percentage of secondary power supplied by the NPUP generation systems 24 a, 24 b may vary based on the power consumption of the aircraft 2. Some factors that affect the power consumption of the aircraft 2 include, but are not limited to, the flight phase of the aircraft 2 (e.g., takeoff, climb, cruise, descent, etc.), various loads on the aircraft 2, and environmental conditions. Some examples of environmental conditions that may affect the power consumption include, but are not limited to, icing conditions, ambient temperature, moisture, and precipitation. Some examples of loads on the aircraft 2 that may affect the power consumption include, but are not limited to, galley ovens, heaters and refrigeration units, lavatories, flight controls, avionics, environmental control systems, and lighting.

The pneumatic system 30 may include the left pneumatic distribution channel 36 a and a right pneumatic distribution channel 36 b. Compressed air may be supplied to the pneumatic distribution channels 36 a, 36 b by the respective pneumatic compressors 44 a, 44 b. Specifically, the left pneumatic compressor 44 a may provide air to the left pneumatic distribution channel 36 a, and the right pneumatic compressor 44 b may provide air to the right pneumatic distribution channel 36 b. Each pneumatic compressor 44 a, 44 b may be integrated or coupled by a gearbox (not shown) to one of the NPUP generation sources 22 a, 22 b. Specifically, the left NPUP generation source 22 a may drive the left pneumatic compressor 44 a, and the right NPUP generation source 22 may drive the right pneumatic compressor 44 b.

The pneumatic compressors 44 a, 44 b may be used to supply compressed air to respective ECSs 50 a, 50 b. Specifically, the left pneumatic compressor 44 a may be connected to the left ECS 50 a through the left pneumatic distribution channel 36 a, and the right pneumatic compressor 44 b may be connected to the right ECS 50 b though the right pneumatic distribution channel 36 b. The pneumatic valves 42 a, 42 b, 42 c may be provided for controlling the amount of compressed air supplied to the ECSs 50 a, 50 b. Specifically, the pneumatic valves 42 a may control the amount of compressed air supplied to the ECS 50 a, the pneumatic valves 42 b may control the amount of compressed air supplied to the ECS 50 b, and a centrally located pneumatic valve 42 c may be provided to cross-connect the left pneumatic distribution channel 36 a with the right pneumatic distribution channel 36 b.

In one embodiment, bleed or compressed air 60 a, 60 b may be extracted from compressors (not shown) of the main engines 20 a, 20 b. The compressed air 60 a, 60 b may supplement the air provided by the pneumatic compressors 44 a, 44 b to the ECSs 50 a, 50 b. The compressed air 60 a, 60 b extracted from the main engines 20 a, 20 b may be at an elevated temperature, and may therefore be cooled by a heat exchanger (not shown in FIG. 3) before flowing to the ECSs 50 a, 50 b. However, the pneumatic compressors 44 a, 44 b may provide a majority of the air required by the ECSs 50 a, 50 b. In one embodiment, the compressed air 60 a, 60 b may be used for wing ice protection. Specifically, the compressed air 60 a may be directed through a left air duct within a leading edge of a left wing (not shown) of the aircraft 2, and the compressed air 60 b may be directed through a right air duct within a leading edge of a right wing (not shown) of the aircraft 2. Each air duct includes holes that direct the hot compressed air to an inside surface of one of the wings, thus preventing the formation of ice. Alternatively, in another embodiment, the wing ice protection system may be electrical. Heating pads or elements may be bonded to an interior surface of the leading edges of the left and right wings (not shown) to melt ice.

In the exemplary embodiment as shown in FIG. 3, the main engines 20 a, 20 b may be pneumatically started based on the air supplied to the pneumatic system 30 from the pneumatic compressors 44 a, 44 b. Specifically, compressed air from the pneumatic distribution channels 36 a, 36 b may be fed to starter turbines (not shown) of the main engines 20 a, 20 b. The starter turbines consequently rotate, thus producing a mechanical shaft output transmitted to shafts (not shown) of the main engines 20 a, 20 b to be started. Although a pneumatic engine start is discussed, it is to be understood that other approaches may be used to start the main engines 20 a, 20 b as well. For example, the main engines may be started by an electrical starter (not shown), a hydraulic motor (not shown), a jet fuel starter (not shown), or a ground pneumatic source (e.g., a start cart). In one embodiment, the main engines may be started using main engine starter generators, which is discussed in the embodiment as shown in FIG. 4.

The electrical system 32 may include the left main engine generator 70 a, the right main engine generator 70 b, the left NPUP generator 72 a, the right NPUP generator 72 b, electrical power feeders 76 a-76 d, and the electrical switches 80 a-80 i. The left main engine generator 70 a may be mechanically coupled to the left main engine 20 a, and the right main engine generator 70 b may be mechanically coupled to the right main engine 20 b by a gearbox (not shown). Alternatively, in another embodiment, the main engine generators 70 a, 70 b may be integrated with one of the main engines 20 a, 20 b. Likewise, the NPUP generators 72 a, 72 b may be integral or coupled to a respective one of the NPUP generation sources 22 a, 22 b.

The aircraft 2 may include multiple independent electrical main engine generators 70 a, 70 b, NPUP generators 72 a, 72 b, and associated power feeders 76 a-76 b in order to meet certification requirements and for safety reasons. For example, in the embodiment as shown in FIG. 3 the aircraft 2 includes four independent generators and power feeders (e.g., electrical main engine generators 70 a, 70 b, NPUP generators 72 a, 72 b, and associated power feeders 76 a-76 b). The switches 80 a-80 i may be used to route electrical power to specific electrical busses 88 a-88 d located on the aircraft 2. The electrical busses 88 a-88 d may be used to transport electrical power to various electrical consumption systems (not illustrated in FIG. 3) that may be coupled to the specific electrical busses 88 a-88 d. The aircraft 2 may include independent electrical busses 88 a-88 d for certification requirements and safety reasons.

Independent power generation systems may be capable of powering aircraft essential electrical loads required for certification of the aircraft 2. Some or all of the independent power generation systems may be capable of powering both essential electrical loads and non-essential electrical loads. For example, in the embodiment as shown in FIG. 3, the aircraft 2 includes four independent power generation systems, namely the two main engine generators 70 a, 70 b and the two NPUP generators 72 a, 72 b. The switches 80 e-80 i may be used to route power to the various electrical busses 88 a-88 d on the aircraft 2 in the event one of the main engine generators 70 a, 70 b or the NPUP generators 72 a, 72 b become inoperative.

The NPUP generators 72 a, 72 b may be rated to generate substantially all of the power required by the electrical system 32 as well as all of the essential and non-essential electrical loads on the aircraft 2. However, the main engine generators 70 a, 70 b may be used as a redundant electrical power source rated to only power essential loads. For example, in one embodiment, the main engine generators 70 a, 70 b may be sized to power the essential aircraft loads if a transient condition occurs which may affect operation of the NPUP generators 72 a, 72 b. Alternatively, in another embodiment, the main engine generators 70 a, 70 b may be sized to power the essential and non-essential loads respectively in the event a transient condition occurs which may affect operation of the NPUP generators 72 a, 72 b. It is to be understood that while FIG. 3 illustrates two main engine generators being used as redundant power, in other embodiments the NPUP generators may be used to power substantially all of the electrical loads within the aircraft, which are described in FIGS. 8-9, and 13-16.

The left hydraulic system 34 a may include a left hydraulic system 78 a connected to a left main engine hydraulic pump 84 a via a left hydraulic distribution channel 82 a, and the right hydraulic system 34 b may include a right hydraulic system 78 b connected to a right main engine hydraulic pump 84 b via a right hydraulic distribution channel 82 b. The main engine hydraulic pumps 84 a, 84 b may be integrated or coupled by a gearbox (not shown) to one of the main engines 20 a, 20 b. Specifically, the left main engine 20 a may drive the main engine hydraulic pump 84 a, and the right main engine 20 b may drive the right main engine hydraulic pump 84 b.

The main engine hydraulic pumps 84 a, 84 b may be used to supply hydraulic power to the hydraulic systems 34 a, 34 b. In the embodiment as shown in FIG. 3, the main engine hydraulic pumps 84 a, 84 b may be rated to provide substantially all of hydraulic power required by the aircraft 2. Specifically, the left main engine hydraulic pump 84 a may be used to provide the hydraulic power required by the left hydraulic system 78 a, and the right main engine hydraulic pump 84 b may be used to provide the hydraulic power required by the left hydraulic system 78 b.

In one embodiment, the electric hydraulic pumps 90 a, 90 b may be used to supplement the main engine hydraulic pumps 84 a, 84 b for periods of time when the main engine hydraulic pumps 84 a, 84 b are inoperative, or during high demand conditions. The electric hydraulic pumps 90 a, 90 b may be optional, and are illustrated in phantom line. The NPUP generators 72 a, 72 b may be used to provide electrical power to the electric hydraulic pumps 90 a, 90 b. Specifically, electrical power may be provided to the left electric hydraulic pump 90 a via a left power converter 92 a, and electrical power to may be provided to the right electric hydraulic pump 90 b via a right power converter 92 b. The power converters 92 a, 92 b may be any type of device for converting electrical power from one form to another such as an AC to DC converter, or a voltage converter for changing voltage values.

FIG. 4 illustrates another embodiment of the secondary power system 110. The aircraft 102 may include a left NPUP generation system 124 a, a right NPUP generation system 124 b, a left main engine extraction system 126 a, and a right main engine extraction system 126 b. Similar to the embodiment as shown in FIG. 3, the secondary power system 110 may include a left aircraft main engine 120 a, a right aircraft main engine 120 b, two NPUP generation sources 122 a, 122 b, a pneumatic system 130, an electrical system 132, and two hydraulic systems 134 a, 134 b. The NPUP generation systems 124 a, 124 b may provide between about sixty percent to about ninety percent of the secondary power required by the consumption system 12 (shown in FIGS. 1-2) located within the aircraft 102 during normal operation. In the exemplary embodiment as shown in FIG. 4, the main engines 120 a, 120 b may be started by an electrical starter, a hydraulic motor, a jet fuel starter, a ground pneumatic source, or main engine starter generators 170 a, 170 b.

The pneumatic system 130 may include a left pneumatic distribution channel 136 a, a right pneumatic distribution channel 136 b, and a plurality of pneumatic valves 142 a-142 c. Compressed air may be supplied to the pneumatic distribution channels 136 a, 136 b by respective pneumatic compressors 144 a, 144 b. The pneumatic compressors 144 a, 144 b may be used to supply the air required by the ECSs 150 a, 150 b. Unlike the embodiment as shown in FIG. 3, compressed air may not be bled from compressors (not shown) of the main engines 120 a, 120 b. Instead, the pneumatic compressors 144 a, 144 b may provide substantially all of the compressed air required by the ECSs 150 a, 150 b. Since compressed air is not bled from the compressors, other devices, such as fluid based or electromechanical de-icers, heater pads or elements may be located on the left and right wings (not shown) and used for wing ice protection.

The electrical system 132 includes the left main engine generator 170 a, the right main engine generator 170 b, a left NPUP generator 172 a, a right NPUP generator 172 b, electrical power feeders 176 a-176 d, and a plurality of electrical switches 180 a-180 i. The NPUP generators 172 a, 172 b may be rated to generally provide power to substantially all of the electrical loads on the aircraft 102. However, similar to the embodiment as shown in FIG. 3, the main engine generators 170 a, 170 b may be used as a redundant power source rated to only power essential loads. For example, in one embodiment, the main engine generators 170 a, 170 b may be sized to support starting of the main engines 120 a, 120 b. In another embodiment, the main engine generators 170 a, 170 b may be sized to support aircraft essential loads if the NPUP generators 172 a, 172 b are inoperative. Alternatively, in another embodiment, the main engine generators 170 a, 170 b may be sized to support aircraft essential loads and non-essential loads in the event the NPUP generators 172 a, 172 b are inoperative.

The left hydraulic system 178 a may be connected to a left main engine hydraulic pump 184 a via a left hydraulic distribution channel 182 a and, and the right hydraulic system 178 b may be connected to a right main engine hydraulic pump 184 b via a right hydraulic distribution channel 182 b. The main engine hydraulic pumps 184 a, 184 b may be rated to generally provide substantially all of the hydraulic power required by the aircraft 102. Specifically, the left main engine hydraulic pump 184 a may be used to provide the hydraulic power required by the left hydraulic system 178 a, and the right main engine hydraulic pump 184 b may be used to provide the hydraulic power required by the left hydraulic system 178 b. In one embodiment, electric hydraulic pumps 190 a, 190 b may be used to supplement the main engine hydraulic pumps 184 a, 184 b in the event the main engine hydraulic pumps 184 a, 184 b are inoperative, or during high demand conditions. The NPUP generators 172 a, 172 b may be used to provide electrical power to the electric hydraulic pumps 190 a, 190 b. Specifically, electrical power may be provided to the left electric hydraulic pump 190 a via a power converter 192 a and to the right hydraulic pump 190 b via a right power converter 192 b.

FIG. 5 illustrates yet another embodiment of the secondary power system 210. The aircraft 202 may include a left NPUP generation system 224 a, a right NPUP generation system 224 b, a central NPUP generation system 224 c, a left main engine extraction system 226 a, and a right main engine extraction system 226 b. Similar to the embodiment as shown in FIG. 3, the secondary power system 210 may include a left aircraft main engine 220 a, a right aircraft main engine 220 b, a pneumatic system 230, an electrical system 232, and hydraulic systems 234 a, 234 b. The secondary power system 210 also includes three NPUP generation sources 222 a, 222 b, and 222 c. The NPUP generation systems 224 a-224 c may provide between about sixty percent to about ninety percent of the secondary power required by the consumption system 12 (shown in FIGS. 1-2) located within the aircraft 202 during normal operation. In the exemplary embodiment as shown in FIG. 5, the main engines 220 a, 220 b may be pneumatically started based on the air supplied to the pneumatic system 230 from pneumatic compressors 244 a, 244 b.

The pneumatic system 230 may include a left pneumatic distribution channel 236 a, a right pneumatic distribution channel 236 b, and pneumatic valves 242 a-242 c. Compressed air may be supplied to the pneumatic distribution channels 236 a, 236 b by respective pneumatic compressors 244 a, 244 b. The pneumatic compressors 244 a, 244 b may be used to supply air to respective ECSs 250 a, 250 b. Similar to the embodiment as shown in FIG. 3, compressed air 260 a, 260 b may be extracted from compressors (not shown) of the main engines 220 a, 220 b. The compressed air 260 a, 260 b may supplement the air provided by the pneumatic compressors 244 a, 244 b to the ECSs 250 a, 250 b. However, the pneumatic compressors 244 a, 244 b may provide substantially all of the air to the ECSs 250 a, 250 b under normal operating conditions. In one embodiment, the compressed air 260 a, 260 b may be used for wing ice protection.

The electrical system 232 may include a left main engine generator 270 a, a right main engine generator 270 b, a left NPUP generator 272 a, a right NPUP generator 272 b, a central NPUP generator 272 c, power feeders 276 a-276 e, and electrical switches 280 a-280 k. The left NPUP generation source 222 a and the right NPUP generation source 222 b act as primary power sources for secondary power. The centrally located NPUP generation source 222 c may be smaller in size when compared to the two NPUP generation sources 222 a, 222 b. The NPUP generators 272 a, 272 b may be rated to generally provide power to substantially all of the electrical loads on the aircraft 202, and the third NPUP generator 272 c may support essential loads. The main engine generators 270 a, 270 b may be sized to support essential loads. The main engine generators 270 a, 270 b may be utilized only after the two primary NPUP generation sources 222 a, 222 b or the NPUP generators 272 a, 272 b have become inoperative.

The left hydraulic system 278 a may be connected to a left main engine hydraulic pump 284 a via a left hydraulic distribution channel 282 a and, and the right hydraulic system 278 b may be connected to a right main engine hydraulic pump 284 b via a right hydraulic distribution channel 282 b. The main engine hydraulic pumps 284 a, 284 b may be rated to provide substantially all of hydraulic power required by the aircraft 202. Specifically, the left main engine hydraulic pump 284 a may be used to provide the hydraulic power required by the left hydraulic system 278 a, and the right main engine hydraulic pump 284 b may be used to provide the hydraulic power required by the left hydraulic system 278 b. In one embodiment, electric hydraulic pumps 290 a, 290 b may be used to supplement the main engine hydraulic pumps 284 a, 284 b in the event the main engine hydraulic pumps 284 a, 284 b are inoperative, or during high demand conditions. The NPUP generators 272 a, 272 b may be used to provide electrical power to the electric hydraulic pumps 290 a, 290 b. Specifically, electrical power may be provided to the left electric hydraulic pump 290 a via a power converter 292 a, and to the right hydraulic pump 290 b via a right power converter 292 b.

FIG. 6 illustrates another embodiment of the secondary power system 310. The aircraft 302 may include a left NPUP generation system 324 a, a right NPUP generation system 324 b, a central NPUP generation system 324 c, a left main engine extraction system 326 a, and a right main engine extraction system 326 b. Similar to the embodiment as shown in FIG. 5, the secondary power system 310 may include a left aircraft main engine 320 a, a right aircraft main engine 320 b, three NPUP generation sources 322 a, 322 b, and 322 c, a pneumatic system 330, an electrical system 332, and hydraulic systems 334 a, 334 b. The NPUP generation systems 324 a-324 c may provide between about eighty percent to about one hundred percent of the secondary power required by the consumption systems 12 (shown in FIGS. 1-2) located within the aircraft 302 during normal operation. In the exemplary embodiment as shown in FIG. 6, the main engines 320 a, 320 b may be started by an electrical starter, a hydraulic motor, a jet fuel starter, or a ground pneumatic source.

The pneumatic system 330 may include a left pneumatic distribution channel 336 a, a right pneumatic distribution channel 336 b, a central pneumatic distribution channel 336 c, and pneumatic valves 342 a-342 c. Compressed air may be supplied to the pneumatic distribution channels 336 a-336 c by respective pneumatic compressors 344 a-344 c. The pneumatic compressors 344 a-344 c may be used to supply air to ECSs 350 a, 350 b. Similar to the embodiment as shown in FIG. 4, compressed air may not be bled from compressors (not shown) of the main engines 320 a, 320 b. Instead, the pneumatic compressors 344 a, 344 b may be used to provide substantially all of the compressed air required by the ECSs 350 a, 350 b. Since compressed air is not bled from the compressors, other devices, such as fluid based or electromechanical de-icers, heater pads or elements may be located on the left and right wings (not shown) and used for wing ice protection.

The electrical system 332 includes a left main engine generator 370 a, a right main engine generator 370 b, a left NPUP generator 372 a, a right NPUP generator 372 b, a central NPUP generator 372 c, power feeders 376 a-376 e, and electrical switches 380 a-380 k. The left NPUP generation system 324 a and the right NPUP generation system 324 b may act as primary power sources for secondary power. The NPUP generators 372 a, 372 b may be rated to generally provide power to substantially all of the electrical loads on the aircraft 302, where the third NPUP generator 372 c supports flight with an inoperative main engine generator 370 a, 370 b, or an inoperative NPUP generation source 322 a, 322 b. The main engine generators 370 a, 370 b may be sized to support essential loads. The main engine generators 370 a, 370 b may be implemented only after the two primary NPUP generation sources 322 a, 322 b or the NPUP generators 372 a, 372 b have become inoperative.

The left hydraulic system 378 a may be connected to a left NPUP hydraulic pump 384 a via a left hydraulic distribution channel 382 a, and the right hydraulic system 378 b may be connected to a right NPUP hydraulic pump 384 b via a right hydraulic distribution channel 382 b. The NPUP hydraulic pumps 384 a, 384 b may be rated to generally provide a substantially all of the hydraulic power required by the aircraft 302 during normal operation. Specifically, the left NPUP hydraulic pump 384 a may be used to provide the hydraulic power required by the left hydraulic system 378 a, and the right NPUP hydraulic pump 384 b may be used to provide the hydraulic power required by the left hydraulic system 378 b. In one embodiment, optional main engine hydraulic pumps 390 a, 390 b may be used to supplement the NPUP hydraulic pumps 384 a, 384 b in the event the NPUP hydraulic pumps 384 a, 384 b are inoperative, or during high demand conditions. The main engine hydraulic pumps 390 a, 390 b may be smaller in size when compared to the NPUP hydraulic pumps 384 a, 384 b.

FIG. 7 illustrates yet another embodiment of secondary power system 410. The aircraft 402 may include a left NPUP generation system 424 a, a right NPUP generation system 424 b, a central NPUP generation system 424 c, a left main engine extraction system 426 a, and a right main engine extraction system 426 b. The secondary power system 410 may include a left aircraft main engine 420 a, a right aircraft main engine 420 b, three NPUP generation sources 422 a, 422 b, and 422 c, a pneumatic system 430, an electrical system 432, and hydraulic systems 434 a, 434 b. In the exemplary embodiment as shown in FIG. 7, the NPUP generation systems 424 a-424 c may provide between about eighty percent to about one hundred percent of the secondary power required by the consumption systems 12 (FIGS. 1-2) located within the aircraft 402 during normal operation. In the exemplary embodiment as shown in FIG. 7, the main engines 420 a, 420 b may be pneumatically started based on the air supplied to the pneumatic system 430 from pneumatic compressors 444 a, 444 b.

The pneumatic system 430 may include a left pneumatic distribution channel 436 a, a right pneumatic distribution channel 436 b, and pneumatic valves 442 a-442 c. Compressed air may be supplied to the pneumatic distribution channels 436 a, 436 b by respective pneumatic compressors 444 a, 444 b. The pneumatic compressors 444 a, 444 b may be used to supply air to respective ECSs 450 a, 450 b. Bleed or compressed air 460 a, 460 b may be extracted from compressors (not shown) of the main engines 420 a, 420 b. The compressed air 460 a, 460 b may supplement the air provided by the pneumatic compressors 444 a, 444 b. However, the pneumatic compressors 444 a, 444 b may provide most of the air to the ECSs 450 a, 450 b. The compressed air 460 a, 460 b may be used for wing ice protection.

The electrical system 432 includes a left main engine generator 470 a, a right main engine generator 470 b, a left NPUP generator 472 a, a right NPUP generator 472 b, a central NPUP generator 472 c, power feeders 476 a-476 e, and a plurality of electrical switches 480 a-480 k. The left NPUP generation system 424 a and the right NPUP generation system 424 b may act as primary power sources for secondary power. The centrally located NPUP generation source 422 c may be smaller in size when compared to the two NPUP generation sources 422 a, 422 b. The NPUP generators 472 a, 472 b may be rated to generally provide power to substantially all of the electrical loads on the aircraft 402, where the third NPUP generator 472 c may support essential loads in the event one of the NPUP generators 472 a, 472 b become inoperative. The main engine generators 470 a, 470 b may be sized to support essential loads. The main engine generators 470 a, 470 b may be implemented only after the two primary NPUP generation sources 422 a, 422 b or the NPUP generators 472 a, 472 b have become inoperative.

The left hydraulic system 478 a may be connected to a left NPUP hydraulic pump 484 a via a left hydraulic distribution channel 482 a, and the right hydraulic system 478 b may be connected to a right NPUP hydraulic pump 484 b via a right hydraulic distribution channel 482 b. In one embodiment, two optional auxiliary NPUP hydraulic pumps 490 a, 490 b may be provided. Both of the optional auxiliary NPUP hydraulic pumps 490 a, 490 b may be driven by the centrally located NPUP generation source 422 c. The left auxiliary NPUP hydraulic pump 490 a may be used to supplement the left NPUP hydraulic pump 484 a, and the right auxiliary NPUP hydraulic pump 490 b may be used to supplement the right NPUP hydraulic pump 484 b. The NPUP hydraulic pumps 484 a, 484 b may be rated to generally provide a majority of the hydraulic power required by the aircraft 402, and the auxiliary NPUP hydraulic pumps 490 a, 490 b may be used to supplement the NPUP hydraulic pumps 484 a, 484 b. The auxiliary NPUP hydraulic pump 490 a, 490 b may be smaller in size when compared to the NPUP hydraulic pumps 484 a, 484 b.

FIG. 8 illustrates another embodiment of the secondary power system 510. The aircraft 402 may include a left NPUP generation system 524 a, a right NPUP generation system 524 b, and two centrally located NPUP generation systems 524 c, 524 d. The secondary power system 510 may include four NPUP generation sources 522 a-522 d, a pneumatic system 530, an electrical system 532, and hydraulic systems 534 a, 534 b. The NPUP generation systems 522 a-522 d may provide substantially all of the secondary power (i.e., one hundred percent) required by the consumption systems 12 (FIGS. 1-2) located within the aircraft 502 during normal operation. Thus, aircraft main engines 520 a, 520 b may not be part of the secondary power system 510. In the exemplary embodiment as shown in FIG. 8, the main engines 520 a, 520 b may be started by a jet fuel starter or a ground pneumatic source.

The pneumatic system 530 may include a left pneumatic distribution channel 536 a, a right pneumatic distribution channel 536 b, two central pneumatic distribution channels 536 c-536 d, and pneumatic valves 542 a-542 e. Compressed air may be supplied to the pneumatic distribution channels 536 a-536 d by respective pneumatic compressors 544 a-544 d. The pneumatic compressors 544 a-544 d may be used to supply air to ECSs 550 a, 550 b. Bleed or compressed air may not be extracted from compressors (not shown) of the main engines 520 a, 520 b. Instead, the pneumatic compressors 544 a-544 d may be used to provide substantially all of the compressed air required by the ECSs 550 a, 550 b. Since compressed air is not bled from the compressors, other devices, such as fluid based or electromechanical de-icers, heater pads or elements may be located on the left and right wings (not shown) and used for wing ice protection.

The electrical system 532 may include a left NPUP generator 572 a, a right NPUP generator 572 b, two central NPUP generators 572 c-572 d, power feeders 576 a-576 d, and a plurality of electrical switches 580 a-580 i. The NPUP generators 572 a-572 d may be rated to provide substantially all of the power required by electrical loads on the aircraft 502.

The left hydraulic system 578 a may be connected to a left NPUP hydraulic pump 584 a via a left hydraulic distribution channel 582 a, and the right hydraulic system 578 b may be connected to a right NPUP hydraulic pump 584 b via a right hydraulic distribution channel 582 b. In one embodiment, two optional auxiliary NPUP hydraulic pumps 590 a, 590 b may be provided as well. Specifically, the left auxiliary NPUP hydraulic pump 590 a may be driven by the left central NPUP generation source 522 c, and the right auxiliary NPUP hydraulic pump 590 b may be driven by the right central NPUP generation source 522 d. In one embodiment, the NPUP hydraulic pumps 584 a, 584 b may be rated to generally provide substantially all of the hydraulic power required by the aircraft 502, where the auxiliary NPUP hydraulic pumps 590 a, 590 b may be smaller in size when compared to the NPUP hydraulic pumps 584 a, 584 b. The auxiliary NPUP hydraulic pumps 590 a, 590 b may be used to supplement the NPUP hydraulic pumps 584 a, 584 b. In another embodiment, the auxiliary NPUP hydraulic pumps 590 a, 590 b may be equal in size when compared to the NPUP hydraulic pumps 584 a, 584 b.

FIG. 9 illustrates yet another embodiment of the secondary power 610. The aircraft 602 may include a left NPUP generation system 624 a, a right NPUP generation system 624 b, two centrally located NPUP generation systems 624 c, 624 d, a left main engine extraction system 626 a, and a right main engine extraction system 626 b. The secondary power system 610 may include a left aircraft main engine 620 a, a right aircraft main engine 620 b, four NPUP generation sources 622 a-622 d, pneumatic systems 630 a, 630 b, an electrical system 632, and hydraulic systems 634 a, 634 b. The NPUP generation sources 622 a-622 d may provide between about eighty-five percent to about ninety-five percent of the secondary power required by the consumption systems 12 (FIGS. 1-2) located within the aircraft 602 during normal operation. In the exemplary embodiment as shown in FIG. 9, the main engines 620 a, 620 b may be pneumatically started based on the air supplied to the pneumatic system 630 from pneumatic compressors 644 a-644 d.

The left pneumatic system 630 a may include a left pneumatic distribution channel 636 a and pneumatic valves 642 a, and the right pneumatic system 630 b may include a right pneumatic distribution channel 636 and pneumatic valves 642 b. Compressed air may be supplied to the left pneumatic distribution channels 636 a by pneumatic compressors 644 a and 644 c, and compressed air may be supplied to the left pneumatic distribution channels 636 a by pneumatic compressors 644 b and 644 d. Unlike the embodiment as shown in FIG. 8, compressed air 660 a, 660 b may be extracted from compressors (not shown) of the main engines 620 a, 620 b. The compressed air 660 a, 660 b may be used for wing ice protection. However, the pneumatic compressors 644 a-644 d may be used to provide substantially all of the air required by the ECSs 650 a, 650 b. Specifically, the pneumatic compressors 644 a and 644 c provide compressed air to the ECS 650 a, and the pneumatic compressors 644 b and 644 d provide compressed air to the ECS 650 b.

The electrical system 632 may include a left NPUP generator 672 a, a right NPUP generator 672 b, two central NPUP generators 672 c-672 d, power feeders 676 a-676 d, and a plurality electrical switches 680 a-680 i. The NPUP generators 672 a-672 d may be rated to generally provide power to substantially all of the electrical loads on the aircraft 602.

The left hydraulic system 678 a may be connected to a left NPUP hydraulic pump 684 a via a left hydraulic distribution channel 682 a, and the right hydraulic system 678 b may be connected to a right NPUP hydraulic pump 684 b via a right hydraulic distribution channel 682 b. In one embodiment, two optional auxiliary NPUP hydraulic pumps 690 a, 690 b may be provided as well. Specifically, the left auxiliary NPUP hydraulic pump 690 a may be driven by the left central NPUP generation source 622 c, and the right auxiliary NPUP hydraulic pump 690 b may be driven by the right central NPUP generation source 622 d. In one embodiment, the NPUP hydraulic pumps 684 a, 684 b may be rated to generally provide substantially all of the hydraulic power required by the aircraft 602, and the auxiliary NPUP hydraulic pumps 690 a, 690 b may be smaller in size when compared to the NPUP hydraulic pumps 684 a, 684 b. The auxiliary NPUP hydraulic pumps 690 a, 690 b may be used to supplement the NPUP hydraulic pumps 684 a, 684 b. In another embodiment, the auxiliary NPUP hydraulic pumps 690 a, 690 b may be equal in size when compared to the NPUP hydraulic pumps 684 a, 684 b.

FIG. 10 illustrates yet another embodiment of the secondary power system 710. The aircraft 702 may include a left NPUP generation system 724 a, a right NPUP generation system 724 b, a left main engine extraction system 726 a, and a right main engine extraction system 726 b. The secondary power system 710 may include a left aircraft main engine 720 a, a right aircraft main engine 720 b, NPUP generation sources 722 a, 722 b, an electrical system 732, and hydraulic systems 734 a, 734 b. The NPUP generation systems 724 a, 724 b may provide between about sixty percent to about eighty percent of the secondary power required by the consumption systems 12 (FIGS. 1-2) located within the aircraft 702 during normal operation.

It should be noted that unlike the embodiments as shown in FIGS. 3-9, the secondary power system 710 may not include a pneumatic system, and may not bleed air from the compressors (not shown) of the main engines 720 a, 720 b. Moreover, the secondary power system 710 may not rely on the NPUP generation systems 724 a, 724 b to provide pneumatic air.

Instead, electric motor driven compressors (EMDCs) 730 a-730 d may be used to provide substantially all of the compressed air required by the ECSs 750 a, 750 b. Since compressed air is not bled from compressors of the main engines 720 a, 720 b, other devices, such as fluid based or electromechanical de-icers, heater pads or elements may be located on the left and right wings (not shown) and used for wing ice protection.

The electrical system 732 includes a left main engine generator 770 a, a right main engine generator 770 b, a left NPUP generator 772 a, a right NPUP generator 772 b, power feeders 776 a-776 d, a plurality of electrical switches 780 a-480 i, electrical busses 788 a-788 d, and power converters 792 a-792 d. The NPUP generators 772 a, 772 b may supply the electrical power to the EMDCs 792 a-792 d via electrical busses 788 b and 788 c and power converters 792 a-792 d. The main engine generators 770 a, 770 b may be sized to support starting of the main engines 720 a, 720 b. Additionally, the main engine generators 770 a, 770 b may be sized to support essential loads. The actual loading of the main engine generators 770 a, 770 b may be managed to minimize the amount of power extracted from the main engines 720 a, 720 b. That is, the main engine generators 770 a, 770 b may be used to either start the main engines 720 a, 720 b or function as electric generators during flight.

The left hydraulic system 778 a may be connected to a left main engine hydraulic pump 784 a via a left hydraulic distribution channel 782 a and, and the right hydraulic system 778 b may be connected to a right main engine hydraulic pump 784 b via a right hydraulic distribution channel 782 b. The main engine hydraulic pumps 784 a, 784 b may be rated to generally provide all of hydraulic power required by the aircraft 702. Specifically, the left main engine hydraulic pump 784 a may be used to provide the hydraulic power required by the left hydraulic system 734 a, and the right main engine hydraulic pump 784 b may be used to provide the hydraulic power required by the left hydraulic system 734 b. In one embodiment, auxiliary electric hydraulic pumps 790 a, 790 b may be used to supplement the main engine hydraulic pumps 784 a, 784 b in the event the main engine hydraulic pumps 784 a 784 b are inoperative, or during high demand conditions. The NPUP generators 772 a, 772 b may be used to provide electrical power to the electric hydraulic pumps 790 a, 790 b. Specifically, electrical power from one of the NPUP generators 772, 772 b may be provided to the left electric hydraulic pump 790 a via a power converter 792 a and to the right hydraulic pump 790 b via a right power converter 792 b.

FIG. 11 illustrates another embodiment of the secondary power system 810. The aircraft 802 may include a left NPUP generation system 824 a, a right NPUP generation system 824 b, a left main engine extraction system 826 a, and a right main engine extraction system 826 b. The secondary power system 810 may include a left aircraft main engine 820 a, a right aircraft main engine 820 b, two NPUP generation sources 822 a, 822 b, an electrical system 832, and hydraulic systems 834 a, 834 b. The NPUP generation systems 824 a, 824 b may provide between about seventy percent to about ninety percent of the secondary power required by the consumption systems 12 (FIGS. 1-2) located within the aircraft 802 during normal operation. Similar to the embodiment as shown in FIG. 10, the secondary power system 810 may not include a pneumatic system, and includes EMDCs 830 a-830 d to provide substantially all of the compressed air required by the ECSs 850 a, 850 b. Since compressed air is not bled from compressors of the main engines 820 a, 820 b, other devices, such as fluid based or electromechanical de-icers, heater pads or elements may be located on the left and right wings (not shown) and used for wing ice protection.

The electrical system 832 includes a left main engine generator 870 a, a right main engine generator 870 b, a left NPUP generator 872 a, a right NPUP generator 872 b, power feeders 876 a-876 d, a plurality of electrical switches 880 a-880 i, electrical busses 888 a-888 d, and power converters 892 a-892 d. The NPUP generators 872 a, 872 b may supply electrical power to the EMDCs 892 a-892 d via electrical busses 888 b and 888 c and power converters 892 a-892 d. The main engine generators 870 a, 870 b may be sized to support starting of the main engines 820 a, 820 b. Additionally, the main engine generators 870 a, 870 b may be sized to support essential loads. The actual loading of the main engine generators 870 a, 870 b may be managed to minimize the amount of power extracted from the main engines 820 a, 820 b.

The left hydraulic system 878 a may be connected to a left NPUP hydraulic pump 884 a via a left hydraulic distribution channel 882 a, and the right hydraulic system 878 b may be connected to a right NPUP hydraulic pump 884 b via a right hydraulic distribution channel 882 b. The NPUP hydraulic pumps 884 a, 884 b may be rated to generally provide substantially all or a majority of the hydraulic power required by the aircraft 802. Specifically, the left NPUP hydraulic pump 884 a may be used to provide the hydraulic power required by the left hydraulic system 878 a, and the right NPUP hydraulic pump 884 b may be used to provide the hydraulic power required by the left hydraulic system 878 b. In one embodiment, optional main engine hydraulic pumps 890 a, 890 b may be used to supplement the NPUP hydraulic pumps 384 a, 384 b or provide relief in the event one of the NPUP hydraulic pumps 384 a, 384 b are inoperative. The main engine hydraulic pumps 890 a, 890 b may be smaller in size when compared to the NPUP hydraulic pumps 884 a, 884 b.

FIG. 12 illustrates yet another embodiment of the secondary power system 910 that may be used to provide secondary power in an aircraft 902. The aircraft 902 may include a left NPUP generation system 924 a, a right NPUP generation system 924 b, a central NPUP generation system 924 c, a left main engine extraction system 926 a, and a right main engine extraction system 926 b. The secondary power system 910 may include a left aircraft main engine 920 a, a right aircraft main engine 920 b, three NPUP generation sources 922 a-922 c, an electrical system 932, and hydraulic systems 934 a, 934 b. The NPUP generation systems 924 a, 924 b may provide between about ninety-five percent to about one hundred percent of the secondary power required by the consumption systems (FIGS. 1-2) located within the aircraft 902 during normal operation. The secondary power system 910 may not include a pneumatic system, and instead includes EMDCs 930 a-930 d to provide substantially all of the compressed air required by the ECSs 950 a, 950 b. Since compressed air is not bled from compressors of the main engines 920 a, 920 b, other devices, such as fluid based or electromechanical de-icers, heater pads or elements may be located on the left and right wings (not shown) and used for wing ice protection. In the exemplary embodiment as shown in FIG. 12, the main engines 920 a, 920 b may be started by a jet fuel starter or a ground pneumatic source.

The electrical system 932 includes a left main engine generator 970 a, a right main engine generator 970 b, a left NPUP generator 972 a, a right NPUP generator 972 b, a central NPUP generator 972 c, power feeders 976 a-976 e, a plurality of electrical switches 980 a-980 k, electrical busses 988 a-988 d, and power converters 992 a-992 d. The left NPUP generation source 922 a and the right NPUP generation source 922 b may act as primary power sources for secondary power. The centrally located NPUP generation source 922 c may be smaller in size when compared to the two NPUP generation source 922 a, 922 b. The NPUP generators 972 a, 972 b may be rated to support substantially all of the electrical loads on the aircraft 902, where the third NPUP generator 972 c may support essential loads. The main engine generators 970 a, 970 b may be sized to support essential loads as well.

The left hydraulic system 978 a may be connected to a left NPUP hydraulic pump 984 a via a left hydraulic distribution channel 982 a, and the right hydraulic system 978 b may be connected to a right NPUP hydraulic pump 984 b via a right hydraulic distribution channel 982 b. In one embodiment, two optional auxiliary NPUP hydraulic pumps 990 a, 990 b may be provided. Both of the optional auxiliary NPUP hydraulic pumps 990 a, 990 b may be driven by the centrally located NPUP generation source 922 c. The left auxiliary NPUP hydraulic pump 990 a may be used to supplement the left NPUP hydraulic pump 984 a, and the right auxiliary NPUP hydraulic pump 990 b may be used to supplement the right NPUP hydraulic pump 984 b. The NPUP hydraulic pumps 984 a, 984 b may be rated to provide substantially all of the mechanical hydraulic power required by the aircraft 902, and the auxiliary NPUP hydraulic pumps 990 a, 990 b may be used provide relief in the event one of the NPUP hydraulic pumps 984 a, 984 b are inoperative, and used during times of high demand. The auxiliary NPUP hydraulic pump 990 a, 990 b may be smaller in size when compared to the NPUP hydraulic pumps 984 a, 984 b.

FIG. 13 illustrates another embodiment of the secondary power system 1010. The aircraft 1002 may include a left NPUP generation system 1024 a, a right NPUP generation system 1024 b, and a central NPUP generation systems 1024 c. The secondary power system 1010 may include three NPUP generation sources 1022 a-1022 c, an electrical system 1032, and hydraulic systems 1034 a, 1034 b. The NPUP generation systems 1024 a-1024 c may provide substantially all of the secondary power required by the consumption systems 12 (FIGS. 1-2) located within the aircraft 1002 during normal operation. Thus, the a aircraft main engines 1020 a, 1020 b may not be part of the secondary power generation system 1010. Moreover, the secondary power system 1010 may not include a pneumatic system, and instead includes EMDCs 1030 a-1030 d to provide substantially all of the compressed air required by ECSs 1050 a, 1050 b. Since compressed air is not bled from compressors of the main engines 1020 a, 1020 b, other devices, such as fluid based or electromechanical de-icers, heater pads or elements may be located on the left and right wings (not shown) and used for wing ice protection. In the exemplary embodiment as shown in FIG. 13, the main engines 1020 a, 1020 b may be started by a jet fuel starter or a ground pneumatic source.

The electrical system 1032 may include a left NPUP generator 1072 a, a right NPUP generator 1072 b, central NPUP generators 1072 c-1072 d, power feeders 1076 a-1076 d, a plurality of electrical switches 1080 a-1080 i, electrical busses 1088 a-1088 d, and power converters 1092 a-1092 f (power converters 1092 e and 1092 f may be optional, and are discussed below). The central NPUP generation source 1022 c may be coupled to both NPUP generators 1072 c and 1072 d. The NPUP generators 1072 a-1072 d may be rated to support all of the electrical loads on the aircraft 1002.

The left hydraulic system 1078 a may be connected to a left NPUP hydraulic pump 1084 a via a left hydraulic distribution channel 1082 a, and the right hydraulic system 1078 b may be connected to a right NPUP hydraulic pump 1084 b via a right hydraulic distribution channel 1082 b. In one embodiment, two optional electrically powered auxiliary NPUP hydraulic pumps 1090 a, 1090 b may be provided. The left auxiliary NPUP hydraulic pump 1090 a may be provided electrical energy by one of the NPUP generators 1072 a-1072 c via the electrical bus 1088 b and the optional power converter 1092 e, and the right auxiliary NPUP hydraulic pump 1090 b may be provided electrical energy by one of the NPUP generators 1072 a-1072 c via the electrical bus 1088 c and the optional power converter 1092 f. The left auxiliary NPUP hydraulic pump 1090 a may be used to supplement the left NPUP hydraulic pump 1084 a, and the right auxiliary NPUP hydraulic pump 1090 b may be used to supplement the right NPUP hydraulic pump 1084 b. The NPUP hydraulic pumps 1084 a, 1084 b may be rated to provide substantially all of the mechanical hydraulic power required by the aircraft 1002, and the auxiliary NPUP hydraulic pumps 1090 a, 1090 b may be used provide relief in the event the NPUP hydraulic pumps 1084 a, 1084 b are inoperative and during times of high demand.

FIG. 14 illustrates yet another embodiment of the secondary power system 1110. The aircraft 1102 may include a left NPUP generation system 1124 a, a right NPUP generation system 1124 b, a central NPUP generation system 1124 c, a left main engine extraction system 1126 a, and a right main engine extraction system 1126 b. The secondary power system 1110 may include a left aircraft main engine 1120 a, a right aircraft main engine 1120 b, three NPUP generation sources 1122 a-1122 c, an electrical system 1132, and hydraulic systems 1134 a, 1134 b. The NPUP generation systems 1122 a-1122 c may provide between about eighty-five percent to about ninety-five percent of the secondary power required by the consumption systems 12 (FIGS. 1-2) located within the aircraft 1102 during normal operation. The secondary power system 1110 may not include a pneumatic system, and instead includes EMDCs 1130 a-1130 d to provide substantially all of the compressed air required by ECSs 1150 a, 1050 b. Since compressed air is not bled from compressors of the main engines 1120 a, 1120 b, other devices, such as fluid based or electromechanical de-icers, heater pads or elements may be located on the left and right wings (not shown) and used for wing ice protection. In the exemplary embodiment as shown in FIG. 14, the main engines 1120 a, 1120 b may be started by a hydraulic motor, a jet fuel starter, or a ground pneumatic source.

The electrical system 1132 includes left NPUP generators 1172 a, 1172 b, right NPUP generators 1172 c, 1172 d, central NPUP generators 1172 e-1172 f, power feeders 1176 a-1176 f, a plurality of electrical switches 1180 a-1180 j, electrical busses 1188 a-1188 d, and power converters 1192 a-1192 f (the power converters 1192 e and 1192 f are optional, and are discussed below). The central NPUP generation source 1122 c may be coupled to both NPUP generators 1172 e and 1172 f. The NPUP generators 1172 a-1172 d may be rated to support all of the electrical loads on the aircraft 1102.

The left hydraulic system 1178 a may be connected to a left main engine hydraulic pump 1184 a via a left hydraulic distribution channel 1182 a, and the right hydraulic system 1178 b may be connected to a right main engine hydraulic pump 1184 b via a right hydraulic distribution channel 1182 b. In one embodiment, two electrically driven optional auxiliary NPUP hydraulic pumps 1190 a, 1190 b may be provided. The left auxiliary NPUP hydraulic pump 1190 a may be provided electrical energy by one of the NPUP generators 1172 a-1172 c via the electrical bus 1188 b and the optional power converter 1192 e, and the right auxiliary NPUP hydraulic pump 1190 b may be provided electrical energy by one of the NPUP generators 1172 a-1172 c via the electrical bus 1188 c and the optional power converter 1192 f. The left auxiliary NPUP hydraulic pump 1190 a may be used to supplement the left NPUP hydraulic pump 1184 a, and the right auxiliary NPUP hydraulic pump 1190 b may be used to supplement the right NPUP hydraulic pump 1184 b. The main engine hydraulic pumps 1184 a, 1184 b may be rated to provide substantially all of the mechanical hydraulic power required by the aircraft 1118, and the auxiliary NPUP hydraulic pumps 1190 a, 1190 b may be used provide relief in the event the main engine hydraulic pumps 1184 a, 1184 b are inoperative and during times of high demand.

FIG. 15 illustrates another embodiment of the secondary power system 1210. The aircraft 1202 may include a left NPUP generation system 1224 a, a right NPUP generation system 1224 b, and a central NPUP generation system 1224 c. The secondary power system 1210 may include three NPUP generation sources 1222 a-1222 c, an electrical system 1232, and hydraulic systems 1234 a, 1234 b. The NPUP generation systems 1224 a-1224 c may provide substantially all of the secondary power required by the consumption systems 12 (FIGS. 1-2) located within the aircraft 1202 during normal operation. Thus, the secondary power system 1210 may not include aircraft main engines 1220 a, 1220 b. Moreover, the secondary power system 1210 may not include a pneumatic system, and instead includes EMDCs 1230 a-1230 d to provide substantially all of the compressed air required by ECSs 1250 a, 1250 b. Since compressed air is not bled from compressors of the main engines 1220 a, 1220 b, other devices, such as fluid based or electromechanical de-icers, heater pads or elements may be located on the left and right wings (not shown) and used for wing ice protection. In the exemplary embodiment as shown in FIG. 15, the main engines 1220 a, 1220 b may be started by a jet fuel starter, or a ground pneumatic source.

The electrical system 1232 includes left NPUP generators 1272 a, 1272 b, right NPUP generators 1172 c, 1172 d, central NPUP generators 1172 e-1172 f, electrical power feeders 1176 a-1176 f, a plurality of electrical switches 1280 a-1280 k, electrical busses 1288 a-1288 d, and power converters 1292 a-1292 f (the power converters 1292 e and 1292 f may be optional, and are discussed below). The central NPUP generation source 1122 c may be coupled to both NPUP generators 1172 e and 1172 f. The NPUP generators 1272 a-1272 d may supply substantially all of the electrical power required by the EMDCs 1292 a-1292 d, as well as substantially all of the electrical loads on the aircraft 1202.

The left hydraulic system 1278 a may be connected to a left main engine hydraulic pump 1284 a via a left hydraulic distribution channel 1282 a, and the right hydraulic system 1278 b may be connected to a right main engine hydraulic pump 1284 b via a right hydraulic distribution channel 1282 b. In one embodiment, two optional electrically driven auxiliary NPUP hydraulic pumps 1290 a, 1290 b may be provided. The left auxiliary NPUP hydraulic pump 1290 a may be provided electrical energy by one of the NPUP generators 1272 a-1272 c via the electrical bus 1288 b and the optional power converter 1292 e, and the right auxiliary NPUP hydraulic pump 1290 b may be provided electrical energy by one of the NPUP generators 1272 a-1272 c via the electrical bus 1288 c and the optional power converter 1292 f. The left auxiliary NPUP hydraulic pump 1290 a may be used to supplement the left NPUP hydraulic pump 1284 a, and the right auxiliary NPUP hydraulic pump 1290 b may be used to supplement the right NPUP hydraulic pump 1284 b. The main engine hydraulic pumps 1184 a, 1184 b may be rated to provide substantially all of the mechanical hydraulic power required by the aircraft 1202, and the auxiliary NPUP hydraulic pumps 1290 a, 1290 b may be used provide relief in the event the main engine hydraulic pumps 1184 a, 1184 b are inoperative, and during times of high demand.

FIG. 16 illustrates yet another embodiment of the secondary power system 1310. The aircraft 1302 may include a left NPUP generation system 1324 a, a right NPUP generation system 1324 b, and two centrally located NPUP generation systems 1324 c, 1324 d. The secondary power system 1310 may include four NPUP generation sources 1322 a-1322 d, an electrical system 1332, and hydraulic systems 1334 a, 1334 b. The NPUP generation systems 1324 a-1324 d may provide substantially all of the secondary power required by the consumption systems 12 (FIGS. 1-2) located within the aircraft 1302 during normal operation. Thus, the secondary power system 1310 may not include aircraft main engines 1320 a, 1320 b. Moreover, the secondary power system 1310 may not include a pneumatic system, and instead includes EMDCs 1330 a-1330 d to provide substantially all of the compressed air required by ECSs 1350 a, 1350 b. Since compressed air is not bled from compressors of the main engines 1320 a, 1320 b, other devices, such as fluid based or electromechanical de-icers, heater pads or elements may be located on the left and right wings (not shown) and used for wing ice protection. In the exemplary embodiment as shown in FIG. 16, the main engines 1320 a, 1320 b may be started by a jet fuel starter or a ground pneumatic source.

The electrical system 1332 may include a left NPUP generator 1372 a, a right NPUP generator 1372 b, two central NPUP generators 1372 c, 1372 d, power feeders 1376 a-1376 d, a plurality of electrical switches 1380 a-1380 i, electrical busses 1388 a-1388 d, and power converters 1392 a-1392 d. The NPUP generators 1372 a-1372 d may supply substantially all of the electrical power required by the EMDCs 1392 a-1392 d, as well as substantially all of the electrical loads on the aircraft 1302.

The left hydraulic system 1378 a may be connected to a left main engine hydraulic pump 1384 a via a left hydraulic distribution channel 1382 a, and the right hydraulic system 1378 b may be connected to a right NPUP main engine pump 1384 b via a right hydraulic distribution channel 1382 b. In one embodiment, two optional auxiliary NPUP hydraulic pumps 1390 a, 1390 b may be provided. In one embodiment, two optional auxiliary NPUP hydraulic pumps 1390 a, 1390 b may be provided as well. Specifically, the left auxiliary NPUP hydraulic pump 1390 a may be driven by the left central NPUP generation source 1322 c, and the right auxiliary NPUP hydraulic pump 1390 b may be driven by the right central NPUP generation source 1322 d. In one embodiment, the NPUP hydraulic pumps 1384 a, 1384 b may be rated to generally provide substantially all of the hydraulic power required by the aircraft 1302, and the auxiliary NPUP hydraulic pumps 1390 a, 1390 b may be smaller in size when compared to the NPUP hydraulic pumps 1384 a, 1384 b. The auxiliary NPUP hydraulic pumps 1390 a, 1390 b may be used to supplement the NPUP hydraulic pumps 1384 a, 1384 b. In another embodiment, the auxiliary NPUP hydraulic pumps 1390 a, 1390 b may be equal in size when compared to the NPUP hydraulic pumps 1384 a, 1384 b.

The disclosed secondary power systems as described and shown in FIGS. 1-16 provide a full-time source of secondary power to at least one of the power systems located within the aircraft, unlike some types of auxiliary power units (APUs) that are currently available. Specifically, some types of APUs currently available may only be used as a back-up or emergency source of secondary power. Instead, secondary power may be extracted from the aircraft's main engines, which reduces the engine total efficiency and thereby increases the specific fuel consumption of the main engines. In contrast, the embodiments as shown in FIGS. 3-7, 9-12, and 14 disclose multiple NPUP generation systems that provide a portion of the non-propulsive power required by the aircraft, which may result in a reduced amount of energy extracted from the aircraft main engine. Moreover, the embodiments as shown in FIGS. 8, 13, and 15-16 disclose multiple NPUP generation systems that provide substantially all of the secondary or non-propulsive power required by the aircraft, thus generally eliminating the need to extract energy from the main engines. Reducing or eliminating energy extracted from the main engines may result in higher main engine efficiency that results in a lower specific fuel consumption (SFC), which in turn reduces main engine emissions.

While the forms of apparatus and methods herein described constitute preferred embodiments of this invention, it is to be understood that the invention is not limited to these precise forms of apparatus and methods, and the changes may be made therein without departing from the scope of the invention. 

What is claimed is:
 1. An aircraft, comprising: a plurality of environmental control systems (ECSs) each requiring compressed air; a plurality of pneumatic compressors, wherein the pneumatic compressors are configured to provide substantially all the compressed air required by the ECSs; a plurality of generators, wherein the generators are configured to provide substantially all the electric power required by the electric consumption systems; at least one secondary power system requiring secondary power; at least two main engines; and a plurality of non-propulsive utility power (NPUP) generation systems, each with a NPUP generation source, and each configured to provide full-time secondary power during operation of the aircraft, wherein the NPUP generation systems are configured to provide at least a portion of the secondary power required by the at least one secondary power system, the pneumatic compressors are each coupled to a corresponding one of the NPUP generation sources, and the plurality of generators are each coupled to a corresponding one of the plurality of NPUP generation sources.
 2. The aircraft of claim 1, wherein the plurality of NPUP generation systems include at least three NPUP generation systems
 3. The aircraft of claim 2, wherein the three NPUP generation systems provide substantially all of the secondary power required by the at least one secondary power system.
 4. The aircraft of claim 1, further comprising at least three NPUP generators each coupled to a corresponding one of at least three NPUP generation sources.
 5. The aircraft of claim 4, comprising of at least three pneumatic compressors, each coupled to a corresponding one of the three NPUP generation sources.
 6. The aircraft of claim 4, wherein the at least three NPUP generators provide substantially all electrical power required by the aircraft.
 7. The aircraft of claim 4, wherein two of the at least three NPUP generators are rated to provide substantially all electrical power required by the aircraft, and a remaining NPUP generator is configured to support flight based on an inoperative NPUP generation source.
 8. The aircraft of claim 1, further comprising a plurality of NPUP hydraulic pumps that are each coupled to one of the plurality of NPUP generation sources.
 9. The aircraft of claim 8, further comprising a plurality of supplementary hydraulic pumps that are each driven by one of the at least two main engines.
 10. The aircraft of claim 8, further comprising a plurality of NPUP hydraulic pumps that are each coupled to one of the plurality of primary NPUP generation sources to provide substantially all hydraulic power with one or more backup hydraulic pumps coupled to a redundant NPUP generation source, with a corresponding coupled redundant generator.
 11. The aircraft of claim 1, wherein the NPUP generation systems include at least two NPUP generation systems and wherein at least two NPUP generators are each coupled to a corresponding one of at least two NPUP generation sources.
 12. The aircraft of claim 11, wherein the at least two NPUP generators provide substantially all electrical power required by the aircraft.
 13. The aircraft of claim 11, further comprising at least two pneumatic compressors each coupled to a corresponding one of the at least two NPUP generation sources.
 14. The aircraft of claim 11, further comprising a plurality of main engine hydraulic pumps that are each coupled to one of the at least two main engines, wherein the main engine hydraulic pumps are rated to provide substantially all hydraulic power required by the aircraft.
 15. The aircraft of claim 14, further comprising a plurality of electric hydraulic pumps that supplement the main engine hydraulic pumps based on the main engine hydraulic pumps becoming inoperative or during high demand operating conditions.
 16. An aircraft, comprising: a plurality of environmental control systems (ECSs) that each use compressed air; a plurality of pneumatic compressors, wherein the pneumatic compressors are configured to provide at least a portion of the compressed air required by the plurality of ECSs; a plurality of generators, wherein the generators are configured to provide at least a portion of the electric power required by the electric consumption systems; at least one secondary power system requiring secondary power; at least two main engines; and a plurality of NPUP generation systems each configured to provide full-time secondary power during operation of the aircraft, wherein the plurality of NPUP generation systems are configured to provide at least a portion of the secondary power required by the at least one secondary power system, and the plurality of pneumatic compressors are each coupled to a corresponding one of the plurality of NPUP generation sources, and the plurality of generators are each coupled to a corresponding one of the plurality of NPUP generation sources.
 17. The aircraft of claim 16, wherein bleed air is extracted from the at least two main engines, and wherein a portion of the bleed air is supplied to the ECSs.
 18. The aircraft of claim 17, wherein the bleed air is used to provide wing ice protection.
 19. The aircraft of claim 16, wherein the pneumatic compressors are configured to provide substantially all the compressed air required by the plurality of ECSs.
 20. The aircraft of claim 16, wherein the plurality of NPUP generation systems include at least three NPUP generation systems
 21. The aircraft of claim 20, wherein the at least three NPUP generation systems provide substantially all of the secondary power required by the at least one secondary power system.
 22. The aircraft of claim 16, wherein the pneumatic compressor supply air required to pneumatically start the at least two main engines.
 23. A method of providing secondary power in an aircraft, wherein the aircraft includes at least one secondary power system requiring the secondary power and at least two main engines, the method comprising: generating compressed air by a plurality of pneumatic compressors; providing substantially all of the compressed air required by a plurality of environmental control systems (ECSs) by the pneumatic compressors; and generating at least a portion of the secondary power required by the at least one secondary power system by a plurality of NPUP generation systems wherein the NPUP generation systems are configured to provide full-time secondary power during operation of the aircraft.
 24. The method of claim 23, further comprising providing substantially all of the secondary power required by the at least one secondary power system by at least three NPUP generation systems.
 25. The method of claim 24, further comprising providing substantially all electrical power required by the aircraft by at least three NPUP generators, wherein the at least three NPUP generators are each coupled to one of three NPUP generation sources.
 26. The method of claim 24, further comprising providing substantially all electrical power required by the aircraft by two of at least three NPUP generators, wherein a remaining NPUP generator is configured to support flight based on an inoperative NPUP generation system.
 27. The method of claim 24, further comprising coupling each of a plurality of NPUP hydraulic pumps to a corresponding one of the NPUP generation sources.
 28. The method of claim 27, further comprising driving a plurality of supplementary hydraulic pumps by one of the at least two main engines.
 29. The method of claim 24, further comprising coupling an NPUP generator to a corresponding NPUP generation source, wherein the NPUP generation systems include two NPUP generation sources.
 30. The method of claim 29, further comprising providing substantially all electrical power required by the aircraft by the at least two NPUP generators. 